Wire-wrapping machine



Aug. 29, 1950 P. R. HIRSH 2,520,402

WIRE-WRAPPING MACHINE Filed Aug. 18, 1944 4 Sheets-Sheet 1 a2 FIG-1.

M6? Km Aug. 29, 1950 P. R. HIRSH 2,520,402

WIRE-WRAPPING MACHINE Filed Aug. 18, 1944 4 Sheets-Sheet 2 dTTOZR YEY g-29, 1950 I P. R. HIRSH 2,520,402

WIRE-WRAPPING MACHINE Filed Aug. 18, 1944 4 Sheets-Sheet 5 INVEN TOR.P/l/Z/R A.

Wei/(w Patented Aug. 29, 1950 UNITED STATES PATENT OFFICE WIRE-WRAPPINGMACHINE Application August 18, 1944, Serial No. 550,122

11 Claims. 1

This invention relates to the construction of tanks, standpipes, largediameter pipes and like structures and more particularly to machines forapplying tensioned windings about such structures.

Among the objects of the invention is to eifect economies in theconstruction of tanks and other objects made from material such asconcrete which, except for externally applied reinforcing, Would have alow bursting strength.

Another object of the invention is to provide a wire wrapping machinecapable of governing tension in a wire during a winding operation so asto enable maximum utilization of the strength of a given wire, and theapplication of a predetermined tension whereby selection of a suitablewire may be made in the interest of avoiding such waste of material aswould otherwise result by the employment of a wire having strengthgreater than required and by applying the wire under an unknown tension.Another object of the invention is to provide a Wire wrapping machinecapable of wrapping wire uniformly under a predetermined amount oftension so as to enable utilization of the well known principle ofprestressin-g for the purpose of economy in reinforcing steel andimproved functioning of the structure.

The machine of the present invention is capable of exerting any desiredtension in a wire and of maintaining such tension during a wire windingoperation in which the Wire is laid about an object, such as a tank,standpipe, or large diameter pipe. The wire winding and stressingmachine is caused to travel over the surface of an object by cooperatingmechanisms which traverse the machine about the object and at the sametime advance it longitudinally of the axis of the object. The travel ofthe machine circumferentially of the object and longitudinally of theobject is subject to control so that the speed of application of thewire and the pitch of the wire being applied are capable of variationwith respect to each other whereby different requirements ofconstruction may be readily met. The machine is capable of use for theconstruction and reinforcing of tanks and other containers designed forcontaining liquids and materials having diiferent static heads andcontainers having different heights. Other uses of the invention will beapparent from the herein contained description of a form of machine; forexample, a tensioned wrapping can be applied thereby about solidobjects, such as concrete columns and piles.

Further and other objects of the present in vention will be hereinafterset forth in the accompanying specification and claims and demonstratedby the drawings which show by way of illustration a preferred embodimentand'the principle of my invention and what I now consider the best modein which I have contemplated applying that principle. Other embodimentsof the invention employing the same principle may be used and structuralchanges made as desired by those skilled in the art within the spirit ofthe appended claims and without departing from the present invention.

' Referring to the drawings,

Fig. 1 illustrates a front elevation of part of a machine embodying theprinciple of the invention;

Fig. 2 is a side elevation of the machine shown in Fig. 1 with itsassociated wire winding carriage in working position;

Fig. 3 is a top view of the machine shown in Fig. 2;

Fig. 4 is a front elevation of the wire Winding carriage;

Fig. 5 is a horizontal sectional view of mechanism for changing theposition of a guide sheave;

Fig. 6 is a section on line 6-6 of Fig. 5;

Fig. 7 is a schematic view illustrating the manner in which the wire andtension-applying cable is trained over sheaves; and

Figs. 8 and 9 are detail views of a wire clamp.

While the machine is suitable for applying Wire about tanks, standpipes,large diameter pipes and other objects designed for various uses, andhaving walls of different strengths apart from the reinforcing providedby a tensioned winding, a particularly useful application of theinvention is for affording economies in the construction of objectswherein the wall has but little tensional strength, such as, forexample, a wall made of concrete or mortar and having as an integralpart thereof but little or no steel reinforcing. Such objects may bemolded or cast in place wholly by the employment of concrete, or theymay be built up by the application of mortar by projecting devices.After the wall has been constructed, the wall is placed undercompressive stress by the application of a tensioned wire windingagainst its exterior surface. The amount of compression in the materialof a wall for maintaining the wall under compressive stress when thetank is filled, is predetermined, and the winding is applied under suchtensional stress as will meet this condition. Consequently, it isimportant that the exact amount of pro-stressing required is determined.It also is a matter of considerable im- .5 portance that the maximumstrength of available wire be made use of in order that the cost ofmaterials are maintained at a minimum. In order that these objectives beattained, it is of ultimate importance that a machine be able tomaintain the wire required tensional strength to meet the specificationsof a particular job.

An assembled machine is illustrated in the drawings. This includes atraverse control support or frame it (Fig. 1), an elevating platform orelevator H and wire winding mechanism I2 (Figs. 2 and 3). The machine isshown in an operating position opposite a tank 3. The illustrated tankmay be any other kind of vertically standing object about which atensioned wrapping is to be applied.

The support It! is in the form of a skeleton box-like tower which ismade up of structural steel members including four main columns of whichthe front pair 14 and I5 are shown in Fig. 1. The two columns at theback of the frame are similar to the front pair. The front and backpairs of these columns are connected, respectively, by head-beams l6 andll and by foot-beams l8 and I9. Head-beams l6 and I! are connected attheir ends by channel irons 2b and 2!, and similar structural elementsconnect the foot-beams l8 and 59. Columns 14 and i5 are cross-braced bya suitable number of structural elements 22, 23 and 24, but the verticalexpanse between head-beam ii and the foot-beam at the back of the toweris open to provide for the vertical travel of elevating platform l l.The construction Of support lil thusfar described is extended to theleft and right (Fig. l) by frames 25, 26, made up from structuralelements which are rigidly secured to the main columns and thusconstitute parts of the support. Sets of cross-braces 2i and 28, (Fig.2) and other suitable connecting members 29, provide lateral rigidity tothe support;

The support is provided with a pair of bolster blocks 38, M, which carrybearings for pairs of truck wheels 32, 33,-respective1y. Each bolsterthe wall of the tank.

During a wire winding operation the support or tower travels on therails around the tank and causes the wire winding mechanism to wrap Wirearound the tank. The drive for traversing the complete machine mayconsist of a source of motive power mounted anywhere on the machine. Aconvenient location for the driving motor is shown at $2 (Fig. 3) at thelower part of the supporting tower. It is suflicient to provide powerfor driving one wheel of each of the pairs of truck wheels 32 and 33.Shaft 43 for one of the truck wheels 33 is driven from a val"- ablespeed transmission M, (Figs. 1, 2 and 3) through the intermediary of apair of bevel gears 45, vertical shaft 35 and a pair of bevel gears 41,one of which is keyed to truck wheel shaft 43. The bevel gears receivetheir drive from the output shaft of variable speed transmissiontransmission M, which is in turn driven from motor 42 through a chain orbelt and sprocket connection 48.

The power drive to one of truck wheels is obtained from vertical shaft35 through a chain and sprocket connection 5i), including a sprocketwheel 5! on vertical shaft 34. A pair of bevel gears 52 transmit therotation of vertical shaft 34 to shaft 53 by which one of the wheels ofthe pair of truck wheels 32 is driven. It is apparent that the speed oftravel of the supporting tower about the tank may be regulated bychanging the adjustment of the variable speed If the motor fortraversing the machine about the tank is mounted on the elevatingplatform l l, or on the wire winding mechanism l2, and is arranged todrive the rollers I M and l 15 of the wire winding mechanism which bearagainst the exterior of the tank as described hereinafter, then thedriving connections from motor 42 to the truck wheels 32 and 33 may bedispensed with, if desired. Should two traversing drives be used, themotors for each drive preferably would be synchronized so that eachwould exert the same driving influence for traversing the machine.

The elevating platform H includes a pair of stringers 55, 56, which areconnected at their ends by I-bearns 5?, 58, to form a rectangular frame(Figs. 1 and 2). The I-beams extend beyond stringer 56 in cantileverfashion for supporting the winding mechanism carriage opposite the tankwall, as illustrated in Fig. 2. The I- beams carry rails 59, [iii whichprovide support for guiding the wire winding mechanism so that the samemay determine its own position with respect to the supporting tower andplatform. The platform may be boarded over with planks 6| for theconvenience of the operator. The end of the platform remote from thetank is provided with a counterweight 62 for counterbalancing theeccentric weight of the wire winding mechanism.

Between the front and back pairs of columns of the tower, oppositecolumn I4 and column [5, respectively, there is a vertically extendingguide rail 63 and a similar vertical guide rail 64 (Fig. 3). These twovertical guide rails are secured to the tower and extend from its footto its headbeams. Guide rail 63 is engaged on opposite sides by a pairof rollers or guide blocks 65 which are carried by the elevatingplatform H. A similar pair of .rollers or guide blocks 66 engageopposite sides of vertical guide rail 64.

The platform ii is supported, and its rising and lowering movements arecontrolled, by pairs of chains at each end of the platform. Chain H3, atthe right side of Fig. 1, has its ends connected to stringer at H Itscompanion chain '52, at the same side of the tower, has its endsconnected to stringer 56 at is (Fig. 2).

The upper extent of sprocket chain 10 passes over a single sprocket 13,and the lower extent of the chain passes over another single sprocket14. Chain Ill also is engaged by idler sprockets 75, 16 and a drivensprocket l! on countershaft 78. It will thus be seen that rotation ofthe countershaft 18 in either direction will cause the right end ofstringer (Fig. 1) to rise or lower, as the case may be.

A similar arrangement of idler and driven sprockets is provided forengaging the companion sprocket chain 12 to enable correspondingmovements of the right end of stringer 56 through operation ofcountershaft '18. As shown in Fig. 2, upper and lower single sprockets19, 80,

idler sprockets 8|, 82 and driven sprocket 88 are mounted in the framefor guiding and actuating sprocket chain I2. Driven sprockets I1 and 83are carried by countershaft I8 which has a driving sprocket and chainconnection 84. This driving sprocket and chain connection 84 is drivenfrom a speed reducer 85.

Speed reducer 85 is directly connected to the power shaft 86 of variablespeed transmission 44 so that its driving effect on the countershaft isdirectly proportional to the speed of motor 42 which is directlyconnected to shaft 86. Since the drive for the traverse of the towerabout a tank is derived through the power output shaft 81 of thevariable speed transmission 44, it is apparent that flexibility isprovided for varying the rate of travel of the machine about the tankwith respect to the elevating rate of the wire winding mechanism and itsplatform II. By varying the rate of circumferential travel of themachine with respect to the elevating rate of the platform, theresultant direction of the movement of the wire winding mechanism overthe surface of the tank can be controlled whereby the pitch of the wirewrapping may be varied at will.

The left end of the platform (Fig. l) is supported, and its rising andlowering movements are controlled through a pair of similarly mountedchains, one of which is shown at 88 in Fig.1. These chains are operabletogether and at the same rate as chains I and I2 during vertical travelof the platform. Chain 88 is connected to the left end of stringer 55 at89 (Fig. 1). Its upper end is trained over a double sprocket 90 and itslower end is trained over a single sprock- Double sprocket 90 is engagedby an endless chain 92 which engages the single sprocket 93 and isdriven thereby. Sprocket 93 is driven through gears 94, 95, the latterof which is keyed to the same shaft to which sprocket I3 is keyed. It isthus apparent that the two ends of stringer 55 will be caused to riseand lower at the same time and at the same rate, the drive for chain 88being derived through chain 82 and chain 10 from the countershaft I8. Achain companion to chain 88 is attached to the left end of stringer 56and it is operated simultaneously therewith from countershaft I8 throughchain and sprocket connections located at the back of the tower which:

are similar to those described for operating chain 88. It is thusapparent that similar elevating and depressing movements aresimultaneously imparted to both ends of platform II.

For lowering the platform, the drive between the power shaft 86 and theoutput power shaft '81 of the variable speed transmission 44 can bediscontinued and the motor 42 driven in the reverse direction, or areverse gear mechanism may be interposed between the motor and variablespeed mechanism shaft 86.

Wire winding mechanism The wire winding mechanism carriage includes abox frame having a lower rectangular frame I00 and an upper rectangularframe IOI connected together by a number of standards such as I02, I03(Fig. 2). The upper and lower rectangular frames and the standards maybe formed from structural elements such as channel irons or angle ironsand as illustrated in the drawings. The box frame is mounted upon andfastened to a supporting rectangular frame I05 (Figs. 2 and 4). BracketsI08, I01 areattached to the frame and carry bearings for roller shaftsI08, I09. Shaft I08 has at its ends rollers H0 and III and shaft I09also has at its ends similar rollers, one of which is shown at II3 (Fig.2) The left hand rollers (Fig. 1) bear upon rail 58 and rollers II I andH3 bear upon rail 50. These rails rest, respectively, upon beams 51 and58 of the platform so that the carriage may be moved horizontally to andfrom the tower and float between the tower and the tank during a wirewinding operation. I

For providing a wheeled contact between the carriage and the tank as themachine travels about the tank there are provided two pairs of rollersH4, H5, mounted, respectively, on vertical shafts H6, H1 (Figs. 3 and4). The shafts are attached to bearings supported by the box frame ofthe carriage. I

The function of the wire winding mechanism is to enable the winding of awire under tension about a tank, standpipe or a large diameter pipe. Anumber of sheaves are provided for guiding the wire during a windingoperation and for cooperation with a tensioning device designed formaintaining the wire under a predetermined tension as it is beingapplied to the object. While the arrangement of the sheaves may bechanged so as to enable the winding of wire in either direction about anobject, I find it convenient to describe the wire winding mechanism asarranged for applying a wire in a clockwise direction as seen fromabove.

In Fig. 'I I have illustrated the course of the wire through the windingand tensioning mechanism. The wire II 3 is supplied from. a spool I I9which is mounted upon a bracket I20 on the carriage. The bracket has aspindle about which the spool may rotate as the wire is drawn from it.In threading the'wire through the Wire winding mechanism it is drawnover sheave I2I and then passes around the object one or more times andthen passes over sheave I22 at the other end of the winding mechanism(Fig. 7). The one or more turns about the object are in advance of thefinal turns of wire which remain on the object as a permanent part ofits construction. In many cases one turn of the wire will suflice butmore can be made in order to assure frictional resistance between spoolH8 and the portion of the wire I23 which comes to the winding mechanismafter it encircles the object.

After passing over sheave I22 the wire passes successively over sheavesI24 and I25, each of which is free to rotate on a fixed shaft. The wirethen passes over fioating sheave I26 and sheaves I21, I28, and I29,which are free to rotate. Shafts of sheaves I2I, I22, I24, I25, I27, I28and I29 are carried upon brackets extending from structural elements ofthe carriage. Theseseven sheaves are idlers for changing the directionof the wire. The positions of sheave I22 and of sheaves I2I and I29 areadjustable for purposes hereinafter described.

Upon leaving sheave I28 the wire passes over sheave I29 and its end isanchored at I30, which is the starting point for the permanent winding.This ordinarily would be located at the lowest point of an object towhich wire reinforcing is to be applied, as shown in Fig. 2. The anchoris a fixed member solidly attached to the exterior of the object.Tension is applied to the wire by the application of force to thefloating sheave I 26.

When the machine is first threaded, sheave I26 is at its most right-handposition, justto the left of sheave I25 (Fig. 7), and a loop of the wireis engaged-thereby; The loop is intermediate :separ'atedwindings;the-temporary advance wind- .ing and the final permanentwinding. Force is iapplied-to sheave I26 through a cable I3I which isattached to a yoke I32. 2 ended from a trolley I33 which carries theyoke and shaft upon which sheave I26 is mounted, the arms of the yokeserving to support the end of the shaft at either side of the sheave.Trolley I33 is provided with a pair of rollers which bear upon theflanges of an H-shaped beamstructure I34. Beam structure I34 is fixed toand is carried by the wire winding carriage and itserves tosupportthewire tensioning mechanism I35 (Figs. 7, 3 and '4). Upon the left endofbeam structure I34 there is mounted a freely rotatable guide sheaveI38 over which cable I3I Thewiretensioning mechanism illustratedcomprises a weighing beam I pivotally mounted at HI :and carrying at itsfree end awinch I42 which is'driven bymotor I43. The cable attached toyoke I32 and passing over sheave 538 extends to winch I42 to whichit isattached. In the operation of the wiretensioning device, the weighingbeam I40 .floats betweencontacts I and I46 which operate-a limit switch'i i'i by which the operation of the'motor is controlled. The weighingbeam 140 maintains cable I3I in tension and the amount of tension can bevaried by changing the load applied on the weighing beam. As the wire iswound about the object, it is extended in length as the result of thetension applied thereto through sheave I26 and this extension is takenup ,by the permissible movement of sheave I26 between sheave I25 andsheave I33 at the end of beam structure I34. In travelling from itsextreme right-hand position to its extreme lefthand position, as shownin Fig. 7, cable I 3I is being taken up by winch I42 under the operationof the motor I43, which is started when contact I45 operates switch I I!as the weighing beam drops. The operation of the motor is discontinuedwhen weighing beam I40 rises sufficiently to cause contact I46 tooperate switch I41 and break the motor connection.

When a wire winding operation has proceeded to such an extent thatsheave I26 has reached the end of its travel, it becomes necessary tostop the Winding operation so as to place sheave I26 'atits startingposition just to the left of sheave .-I25.

The operation of the machine is discontinued for this purpose and wireH8 is temporarily clamped to the frame of the carriage by clamps I50,151 which are secured to brackets I52 and I53, respectively. By theseclamping means, the wire permanently wound about the object and whichcomes to the carriage over sheave I29, and the portion of the wire whichcomes to the carriage over sheave I22 can be held without loss oftension so that the opera- .tion of the wire tensioning device I35 maybe temporarily discontinued. Upon effecting this clamping, and therelease of tension in cable I3I, sheave I26 can be moved to its startingposition at the left of sheave I25, a section of wire of by compressionthereupon and frictionally engages bothends.

This yoke is susand rollers H4 and H5.

:After the wire has been spliced, the operating tension may be reappliedto the wire lay exertin the proper amount of pull on cable I3I bycausing operation of the tension applying mechanism I35. Thereafter theclamping effect of clamps I50 and I5I on the spliced wire is removedandthe machine is ready for continuing the winding operation under the sameconditions of tension that prevailed before making the splice. When thesupply of wire from spool H9 is exhausted,

the empty spool may bereplaced by a filled spool and its wire spliced tothe end of the wire temporarily encircling the tank between sheaves-'I2I and I22.

Clamp I50 also may be used temporarily as a brake on the wire when themachine is being set up to provide sufficient frictional hold on theobject by the wrapping between spool H9 and sheave I22 to resist theload'to be applied b the tensioning mechanism.

Guide sheaves I2I, I29 and I22 maybe mounted on permanently positionedshafts but I sprefer to mount them on supports which will permit theirpositions to be adjusted vertically :to enable the wire winding machineto start wrapping an object at its bottom and to endxthe wrapping at itstop. As shown in the drawings, particularly in Figs. 2 and l, thepositions of these sheaves are close to the lower part of the carriageand in this position the beginning .of

.the wrapping can start at the bottom of the object, as shown in .Fig.2. Except for the last turns at the top of theobject, these sheaves'mayremain, if desired, in the positions illustrated in the drawings, but inorder to complete the winding-of the object at its 'top end, provisionis made for moving the sheaves to the upper portion of the carriage.This is desirable because the exterior of the object laterally sup-;mamtained taut while at the same time it is I ports the carriage byreason of the pressure exerted by the tensioned wire on the carriageSheaves I2I and I29 are supported and moved similarly to sheave I22 andit will suffice to explain the operating and supportng structure for thelatter sheave.

Sheave I22, Figs. 3, 4, 5, 6 and 7, is supported on a stud shaft I56which is carried by a slide I51. Parallel rails I58 and I59 are providedfor guiding the slide. The slides are fastened to a plate IIiI which issecured to the carriage. The slide has fastened to it the ends of anendless chain I62 which passes over sprocket wheels I63, I64 carried byplate I6I. Sprocket wheel I63 is keyed to .a shaft carrying a worm wheelI65 which is engaged by a worm I56. The shaft of worm I66 is connectedto a shaft I61 having hand wheels I68, I69 which are readily accessibleto an operator. The mechanism for adjusting the position of the sheavesI2I and I29 along guide rails I70, "I at the other end of the carriageis arranged and constructed similarly to that for adjusting the positionof sheave I22, and its worm wheel shaft is similarly connected to handwheel shaft I61. The worm gears and worms are of the self-locking typewhereby the sheaves are held in any set position. a It is apparent fromthe description .of operation of the mechanism for changing thepositions of sheaves I2I, I22 and I29 that the spacing of the wrappingsof wire about the ob- .ject can be changed independently of any changein the elevaton of platform II. This may be accomplished under manualcontrol by .9 having an operator gradually lift the sheaves by turningone of the hand wheels I68, I69 as the tower is traversing about theobject. The upper limit of movement of the sheaves, with respect to thecarriage, need be sufficient only to permit winding to a point justabove the uppermost rollers H4, H by which the carriage is supportedagainst the object under the influence of the tensioned wrapping.

When the last turn of Wire has been laid against the object, the machineis stopped and the wire is securely fastened to an anchor fixed to theobject. When the wire is secured, the tension on the wire is releasedand the end of the wire beyond the anchor is cut.

If it should be considered desirable, turns of wire about the object maybe occasionally anchored to members fixed in the wall of the object, butthis practice is not deemed indispensable because the present inventionenables the tensioning of wire about an object within desired limitswhich are carefully computed beforehand and therefore are known to bebelow the maximum breaking strength of the wire.

What is claimed is:

1. A machine for applying wire about a tank or like stationary object,comprising a structure having a vertical height at least as high as anobject about which a wire is to be wrapped, a track for guiding saidstructure about said object, means including wheels supporting saidstructure on said track, a wire-wrapping mechanism, means carried bysaid structure of elevating said wire-wrapping mechanism, and means foradvancing said structure over said track, said lastnamed means includinga motor and connections from said motor to said wheels for driving saidwheels to propel said wire-winding mechanism by advancement of saidstructure.

2. A machine for applying wire about a tank or like stationary object,comprising a structure having a vertical height at least as high as anobject about which a wire is to be wrapped, a track for guiding saidstructure about said object, means including Wheels supporting saidstructure on said track, an elevator, means carried by said structurefor guiding said elevator for vertical travel, means for actuating saidelevator along said guiding means, and means for actuating saidstructure over its track, said lastnamed means including a motor andconnections from said motor to said Wheels for driving said wheels topropel said elevator about said object by movement of said structureover said track.

3. A machine for applying a wire about a tank or like stationary object,comprising a structure adapted to travel in a path concentric to theobject, an elevator carried thereby, means on said structure for guidingsaid elevator opposite the surface of said object, a track carried bysaid elevator and extending normal to the surface of the object, acarriage mounted on said track, a wire-wrapping mechanism on saidcarriage, and rollers carried by said carriage for engaging the surfaceof said object during a wire winding operation.

4. In a machine for wrapping a wire about an object, the combinationcomprising a carriage having sheaves adapted to engage a loop of wirewith reaches which extend between the sheaves and opposite sides of anobject, means including a cable attached to one of said sheaves wherebytension may be applied to said loop of wire, guide sheaves for saidreaches of wire, adjustable supports on said carriage for said guidesheaves, and

actuatable means for changing the positions of said adjustable supportson said carriage while tension is maintained in said wire whereby thelocations of said reaches of wire may be changed 5 with respect to saidcarriage,

5. In a machine for wrapping a wire about an object, the combinationcomprising a carriage having sheaves adapted to engage a loop of wirewith ,reaches which extend between the sheaves and opposite sides of anobject, all of said sheaves being idlers providing for the free runningthereover of said wire and the training of said wire through saidcarriage, a platform, means having connection withsaid platform andsaid. carriage for enabling movement of the carriage laterally ofitself, rollers on said carriage for providing support for the carriageagainst an object to be wrapped with wire' and travel of the carriageover the surface of said object, the axes of said rollers being atsubstantially right angles to the permissible direction of movement ofsaid care riage on said means, and means separate from said sheaves andsaid Wire for causing said carriage to travel on said rollers during awire-wrapping operation, said last-named means being operativelyconnected to said platform to move said platform and said carriage in adirection perpendicular to the axes of said rollers and about saidobject. t

.6, In a machine for wrapping a wire about an object, the combinationcomprising a carriage adapted for relative movement with respect to thesurface of a bodyto be wrapped with wire, means carried by said carriagefor engaging a loop of wire having reaches which constitute extensionsfrom separated windings of the line about theob 'ect said meansincluding an idler sheave engaging said loop of Wire, said loop of wireand reaches being an intermediate portion of a wire wrapped about saidobject, means for exerting force on saidsheave for applying tension tosaidloop of wire, tension-applying means, carried by said carriage andattached to said force-exerting means, rollers carried by said carfromseparated windings about the object, said loopof Wire and; continuationsconstituting an intermediate portion of a 'wire Wrapped about 0 saidobject, means carried by said carriage for applying: tension in saidloop of wire, means cooperating with said carriage and bearing againstthe surface of said object for wholly supporting said carriage during awire-wrapping operation,

5 and means separatefrom said tension-applying meansand, said wire to;traverse said carriage over the surface 1 of said object during awirewrapping operation, said last-named means being driven independentlyof the tension in said loop of wire.

8. A machine for applying a wire about a tank or like stationary object,comprising a structure adapted to travel in a path concentric to a tank,an elevator mounted on said structure, means for moving and guiding saidelevator vertically in rewrapping mechanism including sheaves forengaging a loop of wire formed by continuations Certificate ofCorrection Patent No. 2,520,402 August 29, 1950 PHILIP HIRSH It ishereby certified that error appears in the printed specification of theabove numbered patent requiring correction as follows:

Column 8, line 74, for elevaton read elevation; column 9, line 33, forthe Word of read for;

and that the said Letters Patent should be read as corrected above, sothat the same may conform to the record of the case in the PatentOfiice.

Signed and sealed this 14th day of November, A. D. 1950.

THOMAS F. MURPHY,

Assistant Commissioner of Patents.

